The present invention relates to a force sensing insole which is adapted to be placed inside a shoe so as to provide electrical signals which are useful in the analysis of the walking or running gait of the wearer.
In recent years, devices for the electronic recording of human joint motions have been developed and which are useful in determining the functional level of a patient. One such present device, commonly referred to as an electro-goniometer, permits three mutually orthogonal rotations to be recorded, namely at the hip, knee, and ankle of a patient. These measurements are achieved by the use of precision potentiometers which serve as motion transducers, and the outputs of the potentiometers are transmitted to a recording device which records the signals on a strip chart. A device of this general type is currently marketed by Chattex Corporation of Chattanooga, Tenn., under the trademark "TRIAX". The "TRIAX" electro-goniometer also includes a foot switch which is attached to the bottom of a standard tennis shoe, and which is worn by the patient during testing. The foot switch generates signals which are representative of the timing of the heel strike, heel lift off, ball strike, and ball lift off, which are also useful in the gait analysis.
While the present "TRIAX" electro-goniometer has proven to be useful in many applications, the design of the foot switch has been a source of difficulty, since the position of the switch on the bottom of the standard tennis shoe often changes the relative elevation between the two shoes of the wearer, which in turn may alter the gait of the wearer.
It is accordingly an object of the present invention to provide a foot switch for an electro-goniometer which avoids the above noted disadvantage of the present design.
It is a more particular object of the present invention to provide a force sensing insole which is adapted for use as a foot switch with an electro-goniometer, which is of simple and inexpensive construction, and which is adapted for use inside the patient's own footwear so as to eliminate any height differential between the wearer's shoes, and so as to also eliminate any alteration of the natural gait of the wearer.